Formation of ring patterns surrounded by ripples by single-shot laser irradiation with ultrashort pulse width at the solid/liquid interface

A single pulse (pulse width: 200 fs) was irradiated onto a water/silicon interface. The processed surface had many ring patterns surrounded by sinusoidal patterns within the irradiated spot. The diameter of their rings ranged from 500 nm to 10 μm. It was proposed that the oscillation of a bubble at the interface emitted an acoustic wave around itself and that the melted silicon surface, deformed due to acoustic pressure, solidified instantaneously in the course of the propagation of the acoustic wave on the silicon surface.